(one's) better half
One's spouse or romantic partner. I'd love to come out with you guys after work, but I'd better check in with my better half to make sure we don't have any plans for this evening. The work retreat is meant to be for couples, so be sure to bring your better half!
one's better half
Fig. one's spouse. (Usually refers to a wife.) I think we'd like to come for dinner, but I'll have to ask my better half. I have to go home now to my better half. We are going out tonight.